In a “transparent interconnection of lots of links” (TRILL) network, a customer accessing the TRILL network in a dual-homing manner through a local area network (LAN) bridge may encounter the following scenario: When a customer packet is broadcast on the LAN bridge, two copies of the packet may enter the TRILL network, which may cause a traffic loop. In order to avoid this problem, the TRILL protocol specifies that a Hello packet may be sent mutually between two routing bridges (RB), such as RB1 and RB2, for negotiating a designated routing bridge (DRB). In the DRB obtained through the negotiation, one of the two RBs may be appointed as an appointed forwarder (AF) of a customer virtual local area network (VLAN) for forwarding the traffic. The meaning of the AF lies in that: If a RB is not an AF of a certain customer VLAN, the RB is prohibited from forwarding the traffic of the customer VLAN.
The designation of the AF may change over the time. For example, it is assumed that a TRILL network has two routing bridges RB1 and RB2, and the RB1 is appointed as an AF of a customer VLAN. This means when the traffic of the customer VLAN (C-VLAN) reaches the RB1, it is forwarded by the RB1; while when same traffic reaches the RB2, it is discarded by the RB2.Then, the RB1 is changed to be a non-AF of the customer VLAN and the RB2 becomes an AF. After the change, when the traffic from the customer VLAN reaches the RB2, it is forwarded by the RB2, while when the same traffic reaches the RB1, it is discarded by the RB1.
However, a LAN bridge cannot perceive a change of the AF attribute of a customer VLAN RB in a TRILL network. For example, in the foregoing assumed scenario, the RB1 has been changed from the AF to the non-AF, but the LAN bridge may still send a packet of the customer VLAN to the RB1. Since, at this time, the RB1 is no longer the AF of the customer VLAN, the packet is discarded by the RB1. If the traffic of the customer VLAN reaches a TRILL network through a layer 2 unicast at the LAN bridge, a service may be interrupted at this time.
In order to solve problems of customer traffic switch and service interruption caused by AF attribute change of an RB in a TRILL network, in the prior art, a method is proposed for recovering a service through a media access control (MAC) address aging mechanism of an LAN bridge. However, the default time of MAC address aging is 10 minutes. Therefore, the method provided in the prior art may result in a longer service interruption time, which greatly affects the reliability of a customer unicast service and user experience.